Elihii thomson



(No Model.)

B. THOMSON.

AUTOMATIC OUT-OUT FOR ELECTRIC APPARATUS. No. 307,818. Patented Nov. 11,1884.

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UNITED STATES PATENT OFFICE.

ELIHU THOMSON, OF LYXN, MASSACHUSETTS, ASSIGNOR TO THE THOMSON- HOUSTONELECTRIC COMPAXY, OF CONNECTICUT.

AUTOMATIC CUT-OUT FOR ELECTRiC APPARATUS.

SPECIFICATION forming part of Letters Patent No. 307,818, dated November11,1884.

Application filed April 12, 1884. (X model.)

T 0 aZZ whom it may concern.-

Be it known that I, ELI'HU Tnorrsox, a citizen of the United States, anda resident of Lynn, in the county of Essex and State of Massachusetts,have invented certain new and use ful Improvements in Automatic Cut-Outsfor Electric Apparatus, of which the following is a specification.

My invention relates to means for forming a safety or branch circuitaround an electric lampsuch, for instance, as an arc lamp-or otherelectric apparatus in case the continir ity of the circuit therethroughbe threatened by a break of the connections in said lamp, or by theoccurrence of an abnormally-high re sistance insome portion of thelamp-circuit.

My invention is intended, primarily, for application to electric-arclamps, and is herein shown as arranged to work upon the occurrence of anabnormally-high resistance at the are between the electrodes.

The invention consists in effecting an auto matic cutting out orshort-circuiting of the lamp by the agency (direct or indirect) of anelectric current caused to pass through a vacu ous space between twoelectrodes, contacts, or sets of contact-points, connected,respectively, to opposite sides of the lamp or the electrodes therefor,when the circuit through the lamp or electrodes becomes broken or itsresistance be comes abnormally high, so that current will be forced toleap across the vacuous space between the points.

Some of the ways in which my invention may be carried into practice areshown in the ac companying drawings, in which Figure l illus trates,diagrammatically, an arrangement of circuits or apparatus for thepurpose. Figs. 2, 3, and 4 show modified forms of the electrodes to beused in the vacuous space. Fig. 5 shows an arrangement the equivalent ofthat shown in Fig. 1.-

G, Fig. 1, indicates a globe or receptacle of any suitable kind, intowhich are introduced wires carrying electrodes, points, or metallicprojections placed very near togethersay one-fiftieth of an inch orless. The globe G is exhausted to a vacuum of nearly or quite themaximum conductivity and then finally sealed. The vacuum can be producedby any ordinary good air-pump. The wires are connected, re-

spectively, to the two wires leading to the carbons of anclectric-arclamp, respectively. The connection to one of the carbons ismade through a switchingunagnet, F, and a contact 5 5 closed by theaction of the latter, as shown. The wire X to the other carbon branchesto G, to the rod R, and to the armature or upper contact at K, theclosure of which contact by magnet F shunts the are E and retains F incircuit to hold the contact K closed. Vhen magnet F is not energized,the contact K is held open by a spring, S.

Figs. 2, 3, and r show modifications of the points or plates in G, andwill explain themselves. A magnet, M, may be used near the are E, toassist in displacing it. and so estab lish a large difference ofpotential of the carbons, even though a short space only exist betweenthem.

The operation is as follows: Along are at E, from failure to feed,finally results in the establishment of such a difference of potentialthat a leak occurs through the vacuous space in G, thus energizing themagnet F, and shunting the arc and also G at K, after which the carbonsat E remain cut out. Should contact again be formed at E, the magnet Fis shunted thereby, and releases its armature and opens the contacts atK.

I do not limit myself to any particular device for effecting the closureof the shunt or safety circuit by the agency of the current forcedacross the vacuous space by an abnorinal increase of potential at thesealed elec trodes, as my invention consists, essentially, in combiningsuch scaled electrodes with the lamp or other apparatus in such way asto cause a current to flow from one to the other by an increase ofresistance in the lamp,which 9o currentis used as the effective orexciting agent in causing a closure of the safety branch to be made.

Instead of an electro-inagnet, F, responsive to the current flowing inthe vacuous chamber, 5 I may use other dcvices-as, for instance, aresistance-wire, to be heated by the current flowing. One way ofutilizing the heat developed by such current is shown in Fig. 5, wherefindicates a fusible wire in the circuit to the elecrco trodes in G andXV, a spring-actuated switch controlling the contacts K, and normallyheld open by the wire f, attached to the switch and to a fixed support.The fusion or breakage of the wire fby the current made to flow acrossthe vacuous space between the electr )des in (l in the way describedfrees the switch, and the contacts K are thereupon closed by the springacting on the lever XV.

The constructionot' the switch-contacts, the form of the globe, methodof sealing the same, and shape of electrodes therein may be indefinitely varied without departing from the spirit of my invention.

1 am aware that it is well known that at current of electricity ofproper potential will leap across the space between two electrodesnormally out of contact, and that the current will more readily jump thespace if a vacuum of the proper degree be formed between the electrodes.

My invention consists, however, not in the device mentioned per so, butin the arrangement thereof with relation to the electric lamp or otherapparatus whereby a shunting of the latter may be automatically effectedunder abnormal conditions of resistance.

\Vhat I claim as my invention is- 1. In combination with an electriclamp or other electric apparatus, a short-circuiting or shuntingappliance consisting, essenttlly, of electrodes placed very near oneanother, and coneeted, respectively, to opposite sides of the lamp, andswitch devices controlled by the current leaping from one electrode tothe other to switch or shunt the lamp.

2-. In combination with an electric lamp or other electric apparatus, acircuit-changer or shunting-switch, and an electro-responsive devicecontrolling the same, placed in a circuit in which current may flow bybeing forced from terminal to terminal through a small.partially-vacuous space, as and l'or the purpose described.

The combination, with an electric -arc lamp or other electric apparatusin a circuit, of a vacuous receptacle for opposed electrodes, connectedto opposite sides of that portion 01' the apparatus wherein anabnormallyhigh re sistance may occur, as and for the purpose described.

Signed at Lynn, in the county of Essex and State of Massachusetts, this7th day of April, A. I). 1884:.

' ELIHU THOMSON. \Vitnesses:

\V. O. XVAKJQI IELI'),

E. B. Dom".

